SourceLocation.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
 
#include "HAL/Platform.h"
#include "Templates/UnrealTemplate.h"
 
#ifndef UE_INCLUDE_SOURCE_LOCATION
#define UE_INCLUDE_SOURCE_LOCATION !UE_BUILD_SHIPPING
#endif
 
#if UE_INCLUDE_SOURCE_LOCATION && defined(__cpp_lib_source_location)
#include <source_location>
#endif
 
namespace UE
{
    class FSourceLocation
    {
#if UE_INCLUDE_SOURCE_LOCATION
    #ifdef __cpp_lib_source_location
        using FSourceLocationImpl = std::source_location;
    #else // __cpp_lib_source_location
        struct FSourceLocationImpl
        {
            static UE_CONSTEVAL FSourceLocationImpl current(
                const uint_least32_t InLine = __builtin_LINE(),
                const uint_least32_t InColumn = __builtin_COLUMN(),
                const char* const InFile = __builtin_FILE(),
                const char* const InFunction = __builtin_FUNCTION()) noexcept
            {
                FSourceLocationImpl Location;
                Location.Line = InLine;
                Location.Column = InColumn;
                Location.FileName = InFile;
                Location.FunctionName = InFunction;
                return Location;
            };
 
            constexpr FSourceLocationImpl() noexcept = default;
 
            // source location field access
            constexpr uint_least32_t line() const noexcept
            {
                return Line;
            }
            constexpr uint_least32_t column() const noexcept
            {
                return Column;
            }
            constexpr const char* file_name() const noexcept
            {
                return FileName;
            }
            constexpr const char* function_name() const noexcept
            {
                return FunctionName;
            }
 
        private:
            uint_least32_t Line = 0;
            uint_least32_t Column = 0;
            const char* FileName = nullptr;
            const char* FunctionName = nullptr;
        };
    #endif // __cpp_lib_source_location
#else // UE_INCLUDE_SOURCE_LOCATION
        struct FSourceLocationImpl{
            static UE_CONSTEVAL FSourceLocationImpl current() noexcept
            {
                return {};
            }
            constexpr FSourceLocationImpl() noexcept = default;
            constexpr uint_least32_t line() const noexcept
            {
                return 0;
            }
            constexpr uint_least32_t column() const noexcept
            {
                return 0;
            }
            constexpr const char* file_name() const noexcept
            {
                return "";
            }
            constexpr const char* function_name() const noexcept
            {
                return "";
            }
        };
#endif // UE_INCLUDE_SOURCE_LOCATION
 
    public:
        static UE_CONSTEVAL FSourceLocation Current(FSourceLocationImpl Impl = FSourceLocationImpl::current()) noexcept
        {
            return FSourceLocation(MoveTemp(Impl));
        }
 
        // source location field access
        constexpr uint32 GetLine() const noexcept
        {
            return Impl.line();
        }
        constexpr uint32 GetColumn() const noexcept
        {
            return Impl.column();
        }
        constexpr const char* GetFileName() const noexcept
        {
            return Impl.file_name();
        }
        constexpr const char* GetFunctionName() const noexcept
        {
            return Impl.function_name();
        }
 
    private:
        constexpr FSourceLocation(FSourceLocationImpl&& In) noexcept
            : Impl(MoveTemp(In))
        {
        }
 
        const FSourceLocationImpl Impl;
    };
 
}